The present invention relates to a mowing device to be coupled to the rear of a square baler for forming bales from agricultural harvest material. Such a square baler conventionally comprises a press piston which is moveable backwards and forwards in a press channel in order to compact therein harvest material introduced into the press channel, and a knotter for knotting a strand of twine, by which a bale finish-formed in the press channel is held together. The wall of the press channel comprises slots through which the twine is passed. Through these slots, small fragments of the harvest material can escape during the compacting operation and settle outside the press channel, in particular on the knotter, impairing the functionality of the same.
From U.S. Pat. No. 3,020,829, a square baler is known, in which adjacent to a knotter an outlet nozzle of a blower is arranged in order to direct an air stream onto the knotter. Although the deposition of harvest material fragments on the knotter can be slowed down with such an air stream it cannot however be entirely prevented so that the operation of the square baler has to be interrupted from time to time in order to clean the knotter. This impairs the productivity of the baler. It is therefore desirable to be able to make the time intervals between two clean-ups of the knotter as long as possible. Although this is possible to a certain degree by increasing the flow velocity, a powerful blower required for this purpose is expensive and requires a lot of drive energy, which in turn impairs the economy.